Henry (H)

Quantity: Inductance · Category: Derived SI

The henry is the SI unit of inductance — how strongly a coil opposes changes in current by generating back-EMF. One henry produces one volt when the current changes at one ampere per second.

Relation to SI

1 H = 1 Wb/A = 1 V·s/A = 1 kg·m²/(A²·s²)

Examples

• Small radio coils are measured in microhenries.
• Power-supply chokes are typically a few millihenries.
• Large power transformers can reach inductances of several henries.